To employ tritiated NaBH4 for reducing and labeling the presumptive Schiff-base and "aldol"-type cross-links in the aged and cataractous high molecular weight lens proteins, and to identify the type of reduced cross-links employing chromatographic procedures. To isolate and characterize the tritium labeled cross-linked peptides, after proteolysis of labeled protein. To assay the levels of transglutaminase activity in normal rat, as well as normal and cataractous human lenses; and to identify gamma-glutamyl-epsilon-lysine dipeptide cross-links, in the high molecular weight protein fraction from aged normal and cataractous lenses. To employ lens culture for investigating the effect of calcium ionophore on the endogenous activity of transglutaminase, and to assess the formation of high molecular weight proteins in the presence and absence of biologically and pharmacologically important amines.